JP2014120559A - Magnetic material core - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent reduction in removal characteristics of a noise component while reducing a possibility of damaging a coil even when a main body is formed of a magnetic material.SOLUTION: A magnetic material core 10, formed of a magnetic material in a cylindrical shape, includes: a main body 11 whose inner peripheral surface 12 becomes a through-hole 13 through which a bus bar 15 penetrates; and a gap 14 that is disposed along a penetration direction of the bus bar 15 and shields magnetic field generated inside the main body 11 by a current flowing through the bus bar 15.

Description

  The present invention relates to a magnetic core.

  Conventionally, in order to remove a high-frequency noise component caused by a large current flowing through a bus bar, a bus bar is provided with a magnetic core (see, for example, Patent Document 1). By the way, when connecting between terminals with a bus bar, it is necessary to bend the bus bar, but it is difficult to attach the magnetic core to the bent bus bar. Therefore, generally, a magnetic body core is formed by combining them, for example using two core members. In this case, in order to efficiently remove noise components, it is necessary to bring the core members into close contact with each other.

JP 2005-93536 A

  However, the magnetic core is generally formed by sintering a magnetic material. For this reason, the core members cannot be brought into close contact with each other due to sintering shrinkage and the contact surfaces of the core members are not smooth. May decrease. In addition, the magnetic core may be damaged when the core members come into contact with each other due to vibration.

  The present invention has been made in view of the above-described circumstances, and the object thereof is to reduce noise component removal characteristics while reducing the possibility of damaging the coil even if the main body is formed of a magnetic material. It is in providing the magnetic body core which prevents this.

  In the first aspect of the present invention, a cylindrical body is formed of a magnetic material, and an inner peripheral surface thereof is provided as a through-hole through which the bus bar passes, and the main body is provided along the penetration direction of the bus bar. A gap that blocks a magnetic field generated in the main body due to a current flowing through the bus bar. That is, the main body portion is constituted by a single member although it is discontinuous in the gap. For this reason, even if the main body portion is formed by sintering a magnetic material, it is not affected by the shrinkage of sintering. Therefore, it is possible to suppress a reduction in noise component removal characteristics.

According to the second aspect of the present invention, since the first filling member that fills the gap is further provided, the possibility that the main body portion is damaged even when vibration is applied to the magnetic core can be reduced.
In the invention according to claim 3, since the through hole further includes a second filling member that fills a space between the bus bar penetrating the through hole and the main body, the positional relationship between the bus bar and the main body is determined. It is fixed and insulation can be secured.

The figure which shows schematically the magnetic body core by 1st Embodiment A diagram schematically showing the magnetic field generated in the magnetic core The figure which shows schematically the state which provided the 1st filling member in the magnetic body core by the modification of 1st Embodiment. The figure which shows the state which provided the 2nd filling member in the magnetic body core roughly The figure which shows schematically the magnetic body core by 2nd Embodiment A diagram schematically showing the magnetic field generated in the magnetic core The figure which shows the state which provided the 1st filling member in the magnetic body core roughly The figure which shows the state which provided the 2nd filling member in the magnetic body core roughly

A magnetic core according to a plurality of embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
The first embodiment will be described below with reference to FIGS. 1 and 2. The magnetic core according to the present embodiment is used for, for example, a power supply unit of a traveling three-phase AC motor that is a drive source of an electric vehicle or a hybrid vehicle, a power supply unit to a control device of the motor, or the like. Is assumed.

  As shown in FIG. 1, the magnetic core 10 includes a main body portion 11 formed in a square cylinder shape. The main body 11 is made of a magnetic material, and through holes 13 are formed by the four inner peripheral surfaces 12 thereof. In this embodiment, ferrite is adopted as the magnetic material. Further, one gap 14 is formed in the main body 11. The gap 14 is provided along the through hole 13, that is, along the penetration direction of the bus bar 15 as shown in FIG. 2. Thereby, the main-body part 11 is comprised with the single member which became discontinuous only in the site | part in which the gap 14 is formed.

  As shown in FIG. 2, the bus bar 15 is formed of a flat conductive material such as copper, and is used as a current path for connecting terminals in various devices. When a current (noise current) flows through the bus bar 15 in the direction indicated by the arrow E, a magnetic field is generated around the bus bar 15. Then, the magnetic field is taken into the main body 11 formed of a magnetic material and covering the periphery of the bus bar 15 as indicated by an arrow M. At this time, the larger the current flowing through the bus bar 15, the more likely it is that the main body 11 exceeds the ability to take in magnetism (saturation magnetic flux density) and becomes magnetically saturated. And if the main-body part 11 is magnetically saturated, the further noise component removal effect will be lose | eliminated.

  Therefore, a gap 14 is provided in the main body 11 of the magnetic core 10. The gap 14 is formed by one side of the main body portion 11 facing each other through a predetermined distance, and is an area where air with low magnetic permeability exists. For this reason, the gap 14 becomes a magnetic resistance with respect to the magnetic field taken in the main body 11. As a result, the magnetic field taken into the main body 11 is reduced, the magnetic saturation of the main body 11 is suppressed, and the noise component removal efficiency can be improved. Note that the distance of the gap 14 may be appropriately set according to a required noise component or the like.

  According to such a magnetic core 10, the main body 11 is formed of a single member, and only one gap 14 is provided in the main body. For this reason, unlike the conventional configuration, there is no need to bring a plurality of core members into contact with each other, so that a reduction in noise component removal effect due to dimensional accuracy and smoothness does not occur. That is, it is possible to prevent the noise component removal efficiency from decreasing.

Moreover, since the main body 11 is composed of a single member, even when the bus bar 15 is used in an environment where vibration is applied, unlike the conventional configuration, damage due to contact between the core members does not occur. . In other words, if it is the magnetic body core 10 of this embodiment, vibration resistance can be improved. This becomes very significant when used in, for example, an electric vehicle or a hybrid vehicle.
Further, unlike the conventional configuration, it is not necessary to provide a holding member for holding a plurality of core members, so that the product cost can be reduced and the bus bar assembly including the magnetic core 10 can be downsized. Can be planned.

(Modification of the first embodiment)
Hereinafter, a modification of the first embodiment will be described with reference to FIGS. 3 and 4. The configuration of the magnetic core is the same as that of the first embodiment, and will be described with reference to FIG.

  As shown in FIG. 3, a filling member 16 (corresponding to a first filling member) is provided in the gap 14 of the magnetic core 10. The filling member 16 is made of an insulating resin material. As the resin material, a material having a melt temperature viscosity at 200 ° C. of 750 dPa-S, for example, is preferable in order to facilitate injection molding and the like and in consideration of heat resistance. A material such as an elastomer may be used in consideration of vibration-proofing properties, vibration-isolating properties, thermal conductivity, endothermic properties, and the like.

  Moreover, as a material of the filling member 16 and the filling member 17 to be described later, a material having a relatively low thermal conductivity and a material having a relatively high thermal conductivity can be used. As the temperature of the magnetic core 10 increases, the ability to capture a magnetic field decreases. Therefore, if the bus bar 15 generates heat and the heat is transmitted to the magnetic core 10, the noise component removal efficiency may be reduced. That is, in order not to reduce the noise component removal efficiency, it is desirable to form the filling member 16 and the filling member 17 with a material having relatively low thermal conductivity.

  On the other hand, the magnetic core 10 is often used in an environment where the periphery thereof is molded with a resin material or the like, and brought into contact with an external case or the like so that heat can be dissipated. In that case, if the filling member 16 and the filling member 17 are made of a material having a relatively high thermal conductivity, the heat generated in the bus bar 15 is released to the outside, thereby increasing the temperature of the magnetic core 10. Can be suppressed, and a reduction in noise component removal efficiency can be prevented.

Thus, the material of the filling member 16 and the filling member 17 can be appropriately selected according to the required removal efficiency of noise components, the installation environment, and the like.
By using such a filling member 16, even if vibration is applied to the main body 11 of the magnetic core 10, the gap 14 distance is prevented from changing, and the noise component removal efficiency is changed. Therefore, it is possible to prevent the noise component to be removed due to the change of the removal characteristics from being removed. The charging member 16 may be formed of an elastic material, and the filling member 16 may absorb or attenuate vibration.

Further, if the gap 14 is not filled, there is a possibility that the main body 11 may be damaged by vibration. However, the main body 11 is fixed and damaged by filling the gap 14 with the filling member 16. The fear can be reduced.
Moreover, as shown in FIG. 4, you may fill the inside of the through-hole 13 with the filling member 17 (2nd filling member). This filling member 17 can be the same as the filling member 16 filling the gap 14. The filling member 17 can fix the positional relationship between the bus bar 15 and the main body 11, and can insulate the bus bar 15 from the main body 11. Of course, different materials may be used for the filling member 16 and the filling member 17.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to FIGS. 5 and 8. In the second embodiment, the shape of the main body is different from that of the first embodiment.

  As shown in FIG. 5, the magnetic core 20 of the second embodiment includes a main body 21 formed in a substantially cylindrical shape. A through hole 23 is formed by the inner peripheral surface 22. Further, one gap 24 is formed in the main body portion 21. The gap 24 is provided along the through hole 23, that is, along the penetration direction of the bus bar 25 as shown in FIG. 6. Thereby, the main-body part 21 is formed with the single member which became discontinuous only in the site | part in which the gap 24 is formed.

  As shown in FIG. 6, the bus bar 25 has a substantially circular cross section. For this reason, even if the bus bar 25 is bent, the change in the cross-sectional area at the bent portion is not significant, and deformation such as undulation of the bus bar 25 accompanying bending is reduced. If the bus bar 25 has a corner, the cross-sectional area through which current can flow at the corner increases toward the corner and then decreases, and the resistance value of the bus bar 25 changes due to this increase / decrease. Such a change in the resistance value changes the easiness of the flow of the current flowing through the bus bar 25. Therefore, there is a problem in that radiation noise is generated from the current in the changed portion or the current is reflected to generate new noise.

Therefore, by making the cross-sectional shape of the bus bar 25 substantially circular, the resistance value will not change, and radiation noise will be generated, or a new noise component will be generated that reflects the current and flows backwards to the current flow. Can be prevented.
Further, by making the cross-sectional shape of the main body portion 21 substantially circular as in the magnetic core 20 of the present embodiment, it is possible to efficiently take in the magnetic field generated by the current flowing through the bus bar 25, and to further reduce the noise component. It can be removed efficiently. That is, noise component removal efficiency can be improved.

  In this case, as in the modification of the first embodiment, the gap 24 is filled with a filling member 26 (corresponding to the first filling member) as shown in FIG. 7, or the through hole 23 is shown in FIG. May be filled with a filling member 27 (corresponding to a second filling member). As a result, similarly to the modification of the first embodiment, the distance of the gap 24 is prevented from fluctuating, the noise component removal efficiency is changed, and the noise characteristics to be removed are changed due to the change in the removal characteristics. It can be prevented from being removed, and effects such as reducing the possibility of damage to the main body 21 can be obtained.

(Other embodiments)
The present invention is not limited to the above-described embodiments, and can be arbitrarily modified or expanded as follows without departing from the gist thereof.

For example, the bus bar 15 of the first embodiment and the magnetic core 20 of the second embodiment may be combined, or vice versa.
The size of the main body and the bus bar in each embodiment is an example, and the relative size ratio and the like can be arbitrarily set. For example, in the first embodiment, the main body has a substantially square shape in cross section. However, for example, the cross section may have a rectangular shape. The same applies to the shape of the through hole.

  In the drawings, 10 is a magnetic core, 11 is a main body, 12 is an inner peripheral surface, 13 is a through hole, 14 is a gap, 15 is a bus bar, 16 is a filling member (first filling member), and 17 is a filling member ( (Second filling member), 20 is a magnetic core, 21 is a main body, 22 is an inner peripheral surface, 23 is a through hole, 24 is a gap, 25 is a bus bar, 26 is a filling member (first filling member), 27 Indicates a filling member (second filling member).

Claims (3)

A body portion that is formed in a cylindrical shape from a magnetic material, and whose inner peripheral surface is a through-hole through which the bus bar passes,
A gap that is provided in the main body portion along the penetration direction of the bus bar, and that blocks a magnetic field generated in the main body portion by a current flowing through the bus bar;
A magnetic core comprising:   The magnetic core according to claim 1, further comprising a first filling member that fills the gap.   3. The magnetic core according to claim 1, further comprising a second filling member that fills a space between the bus bar penetrating the through hole and the main body in the through hole.

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